What Are Jointers & Planers?

Jointer Description

• A jointer consists of a spinning head with sharp knives built into it, set into a table that can range from 4 inches wide by 4-feet long up to 24 inches wide and 10-feet long. The outfeed table is level with the top of the spinning blades while the infeed table is adjustable, which allows the cabinetmaker to set the infeed table to cut a certain amount off the bottom face of the piece of wood by pushing it over the spinning knives and onto the outfeed table.

Jointer Use

• The primary purpose of a jointer is to flatten the bottom face of a board before feeding the board through the planer. If the board is fed through the planer without jointing it first, the top face will be smoothed, but the board won't be flattened because it will ride on its bottom face through the planer, whether the bottom face is flat or not. Jointers are also used to make edges of boards smooth and flat so that they can be glued together.

Planer Description

• A planer has a spinning head with sharp knives in it like a jointer, but this head is mounted in an adjustable carriage rather than in the table itself. The board is fed through the planer by a power feed, and the spinning knives cut the top surface of the board rather than the bottom surface as on a jointer. Jointers range in size from small, portable jointers that can be taken to job sites up to enormous jointers that weigh hundreds of pounds and can remove 1/4 inch of wood in a single pass.

Planer Use

• While the jointer is most effective at flattening the bottom of a board, the planer is used to smooth the surface and to make the board a consistent thickness. Because the blades are set into a carriage that is set above the table, the board has to pass through an opening between the table on the bottom and the spinning knives on the top, which means that thicker parts of the board will have more material removed, and the board will end up being the same thickness along its entire length.